CVE-2026-55996Network attack vector

Service interruption via unbounded TLS SAN accumulation

Published Aug 5, 2026 · Updated Aug 5, 2026

Denial of service in SUSE Rancher allows remote attackers to interrupt cluster-internal TLS listeners through crafted SNI hostnames. The dynamiclistener library appends every presented SNI hostname to serving-certificate SANs when no effective CN filter is set, allowing unbounded certificate growth. Reaching cattle-cluster-agent port 443 or Rancher port 444 requires the ability to run or enter a pod; excessive SANs eventually make TLS handshakes fail.

CVSS severity4.3
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in SUSE Rancher allows remote attackers to interrupt cluster-internal TLS listeners through crafted SNI hostnames. The dynamiclistener library appends every presented SNI hostname to serving-certificate SANs when no effective CN filter is set, allowing unbounded certificate growth. Reaching cattle-cluster-agent port 443 or Rancher port 444 requires the ability to run or enter a pod; excessive SANs eventually make TLS handshakes fail.

The record

CVE
CVE-2026-55996
Published
Aug 5, 2026
Updated
Aug 5, 2026
Vendor
NeuVector
Product
Rancher
Classifications
CWE-770, T1499.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.11.0 <2.11.16
  2. Affected versionversion=2.12.0 <2.12.12
  3. Affected versionversion=2.13.0 <2.13.8
  4. Affected versionversion=2.14.0 <2.14.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

NeuVector · Rancherversion=2.11.0 <2.11.16; version=2.12.0 <2.12.12; version=2.13.0 <2.13.8; version=2.14.0 <2.14.4

Published CVSS scores

4.3SUSECVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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